Portia Cornell

Portia Cornell

Assistant Professor, Department of Health Services, Policy, and Practice, Brown University
Health Science Specialist, Center of Innovation for Long Term Services and Supports, Providence VA Medical Center

Dissertation Title:  "Policy and Methods in Health Services Research"

This dissertation consists of two policy papers and one methods paper, all grounded in applied, empirical health-services research. The first two papers concern the influence of medical underwriting in the market for long-term care insurance in the U.S. The third presents a framework for evaluating provider preference as an instrumental variable in comparative effectiveness research with multiple treatments, using as an empirical demonstration a study comparing the safety of five atypical antipsychotics and their effects on chronic disease incidence.

In the first paper, I estimate an empirical model of the factors on which firms make decisions to underwrite individuals for long-term care insurance, using data on the health and coverage decisions for applicants at two U.S. firms. I apply the model parameters to a population-based sample to determine what proportion of households of prime ages to purchase long-term care insurance would be able to qualify for policies if they were to apply for coverage. Among the general population, I estimate that 40 percent of individuals would have their applications rejected if they were to apply for long-term care insurance--a rejection rate substantially higher than the rejection rate of 20-25 percent of applicants in the actual market.

The second paper examines policy ramifications of the bounds on coverage in the individual market for long-term care insurance that I establish in paper one. I study two types of policies designed to encourage individuals to purchase long-term care insurance, tax incentives and state Partnership programs, estimating how the effects of differ with respect to individuals’ underwriting probabilities. I exploit variation in the timing of states’ implementation of these policies with difference-in-difference models, and estimate the demand elasticity of long-term care premiums using simulated statewide marginal tax prices as in instrumental variable for individual prices. I find that the response to these policy incentives is highly dependent on individuals' underwriting probabilities: conditional on wealth and income, tax and Partnership have no apparent effect on insurance purchase among low-approval households, and program effect appears to be concentrated among healthier individuals with high approval probabilities. In evaluating reforms for long-term care financing and their potential to increase private insurance rates, as well as reduce financial pressure on public safety-net programs, policy makers need to consider the role of underwriting in the market for long-term care insurance.

The third paper proposes a framework for assessing provider preference as instrumental variables in comparative effectiveness research and describes diagnostic tools to validate (or debunk) a candidate instrument. In an applied analysis, I show how to use these tools to compare multiple treatments. I compare the safety of commonly prescribed atypical antipsychotics using physician prescribing preference as an instrumental variable. Widespread adoption of a basic protocol and road map for validating potential instruments, particularly the use of sensitivity tests and compliers analysis, would improve the quality of comparative effectiveness research.




Graduation Year

Dissertation Committee Member